make sync update adjusted branch to hide/unhide

This completes initial support for --hide-missing, although the
assistant still needs to be updated and it perhaps needs to be sped up,
and maybe there needs to be a way for git-annex get to operate on
missing files. Opened some more todos for those things.

This commit was sponsored by Henrik Riomar.

Assistant/Threads/Committer.hs

@@ -229,7 +229,7 @@ commitStaged msg = do
 		Right _ -> do
 			ok <- Command.Sync.commitStaged Git.Branch.AutomaticCommit msg
 			when ok $
-				Command.Sync.updateSyncBranch =<< getCurrentBranch
+				Command.Sync.updateBranches =<< getCurrentBranch
 			return ok
 
 {- OSX needs a short delay after a file is added before locking it down,